Hydrocracking process



July 31, 1962 J. w. MYERS 3,047,490

HYDROCRACKING PROCESS Filed Nov. 4, 1958 2 FE HYDROCRACKING 2 I ED FIRSTZONE A SEPARATION 6 ZONE W5 HYDROCRACKING SEPARATION SECONDZONE ZONE ,Tz

INVENTOR. u, JW. MYERS lax $4 #M A TTORNEVS at at wince 3,04Z490Patented July SE, 1982 3,047,490 Y HYDRGCR @KKNG llidtlQESS John W.Myers, llartiesville, (thin, assignor to Phillips Petroleum Coinpany, acorporation of Delaware Filed Nov. 4, 11958, tier. No. 771,711 6(Claims. (El. 208-59) This invention relates to hydrocracking ofhydrocarbon feedstocks. More particularly, the invention relates to aprocess comprising a combination of mutually interrelated andinterdependent steps for the hydrocracking of hydrocarbons boiling abovegasoline to produce gasoline boiling range hydrocarbons.

it has been found that when kerosene and gas oil feedstocks boiling inthe range from about 400 to about 1000 F. are catalyticaliy hydrocrackedunder conditions favoring the conversion of naphthenes to the desiredaromatics, there results in addition to the desired gasoline boilingrange aromatics some heavy aromatics which are quite refractory and aretherefore not converted to the desired gasoline boiling rangehydrocarbons under the conditions of the hydrocracking treatment.

It is an object of the invention, therefore, to provide a process forconverting such kerosene or gas oil feedstocks substantially entirely tomore valuable lower boiling hydrocarbons, principally in the gasolineboiling range, in an economical and efficacious manner.

The drawing is a schematic representation of my process.

Other objects, as well as aspects and advantages, of the invention willbecome apparent from a consideration of the accompanying disclosure.

The first step in my integrated process is the hydrocracking of myhydrocarbon feed having a boiling range in the range from 400 to 1000 F.in the presence of a hydrocracking catalyst under conditions favoringthe dehydrogenation of naphthenes, employing a temperature in the rangefrom 800 to 950 F, a pressure in the range from 300 to 1000 p.s.i.a., aliquid hourly space velocity (volumes/volumes/hour) of 02-10 and atleast 1000 cubic feet of hydrogen at standard conditions per barrel ofoil. An additional feedstock to this first hydrocrack ing step is arecycle gasoline fraction derived from a subsequent hydrocracking step,to be discuss-ed later, and the space velocities and hydrogen ratiosmentioned are on the basis of this total combined charge. This step iseffected in hydrocracking zone 1 of the drawing, the hydrocarbon feedhaving a boiling range from 400 to 1000 F. entering in line 2 and therecycle gasoline fraction entering by Way of line 3. The product fromthis first hydrocracking step is withdrawn through line 4i and includeslight ends and gasoline of high octane number and the heavy fractionboiling above 400 F. This product is separated in separation zone 5 intoa gasoline and lighter fraction boiling below 400 F. in line 6 and theheavy fraction boiling above 400 P. which is withdrawn through line 7and introduced through line 3 to hydrocracking zone 9. This heavyfraction contains heavy, refractory aromatic hydrocarbons which arestable and cannot be converted to gasoline boiling range hydrocarbonsunder the conditions of the first hydrocracking step. This heavy cut issubjected in hydrocracking zone 9 to a second hydrocracking step inwhich all of its components can be converted to gasoline boiling rangehydrocarbons (except for some unavoidable light ends formation), in thepresence of a hydrocracking catalyst which can be the same or adifferent catalyst than employed in the first hydrocracking step, underconditions which favor the net hydrogenation of aromatics to naphthenes,employing a temperature in the range from 600 to 780 F, a pressure inthe range from 500 to 2000 p.s.i.a., a liquid hourly spaced velocity inthe range from 0.2l0, and hydrogen in the amount of at least 1000 cubicfeet per barrel of charge. In this hydrocracking step the refractoryaromatics are converted to naphthenes and these are hydrocracked tolower molecular weight products. From the efiluent which is passedthrough line 10 from this hydrocracking step there is separated inseparation zone 11 a cut of the heavier portion of gasoline produced,and this gasoline is recycled through line 3 to the first hydrocrackingstep, as mentioned before. This cut usually has a boiling range from 400F. down to F., but is more often in the range from 400 F. down to about200 F. The lighter portion of the gasoline from the second hydrocrackingstep and the light ends are taken as product through line 12, while theresidue boiling above 400 F. is recycled to extinction through line 13as part of the feed to the second hydrocracking step.

As before stated, the feeds to be treated in my process are hydrocarbonmixtures in the kerosene to gas oil boiling range, boiling in the rangefrom 400 F. to 1000" F., although usually the end point of the feedemployed is not over 800 F. These kerosenes and gas oils, as is Wellknown, contain mixtures of hydrocarbon types, including naphthenes,aromatics, and paraffins.

The advantages of the process of the present invention are apparent.Thus, the heavy refractory materials which can not be converted in thefirst hydrocracking step are hydrogenated and hydrocracked in the secondhydrocracking step to gasoline boiling range materials containingnaphthenes which, when recycled to the first hydro cracking step, can beconverted under the net dehydrogenation conditions of the firsthydrocracking step to valuable aromatics in the gasoline boiling range.The simplicity of the combination of mutually interrelated steps of theprocess of the invention, together with the complete utilization of thefeed to form valuable gasoline boiling range hydrocarbons (except forsome unavoidable formation of light ends), results in a process oftechnical and economic importance.

While it has been stated that the minimum amount of hydrogen employed isat least 1000 standard cubic feet per barrel of oil in each of thehydrocracking steps, it is usually desirable that at least 3500 cubicfeet per barrel of oil be employed. Although the upper limit of hydrogencan vary widely in either hydrocracking step, for economic reasons thereis seldom employed over 40,000 cubic feet of hydrogen per barrel ofcharge.

For each of the hydrocracking steps described herein, specific ranges ofconditions have been set forth as a guide. However, the hydrocrackingconditions which will produce specific effects are well known in theart. It is noted that the conditions in the first hydrocracking step aresuch that there is a net dehydrogenation of naphthenes to aromatics. Itis known, of course, that high temperature favors dehydrogenation, whilehigh pressure suppresses dehydrogenation. Therefore, for any specificfeed the temperatures and pressures in each of the hydrocracking stepsmust be properly correlated for the desired results. For instance, forany particular feedstock, operation of the first hydrocracking step at800 p.s.i.a. will require a higher temperature within the disclosedrange than operation at 500 p.s.i.a. In a like manner, in the secondhydrogenation step, wherein the conditions are to favor hydrogenation ofaromatics to naphthenes, for any specific feed, operation at 780 F. willrequire a higher pressure than will be required for operation at 600 F.Thus, optimum conditions for any specific feedstock can be establishedby mere routine tests over the ranges of conditions disclosed, with suchconditions as a guide, with no need to resort to extensiveexperimentation in order to establish the conditions for Idehydrogenation of naphthenes to aromatics in the first hydrocrackingstep or the hydrogenation of aromatics to naphthenes in the secondhydrocracking step.

Any known hydrocracking catalyst is applicable in either hydrocrackingstep of the present invention. Many such catalysts are available and arewell known. A particular type of catalyst found to be applicable arecatalysts containing from 0.05 to 10 weight percent of a group VIIImetal selected from the group consisting of platinum, palladium,rhodium, iridium, nickel, and cobalt, deposited on a solid inorganicmetal oxide cracking component, such as, for instance silica-alumina oralumina. Preferably, however, the cracking component is a materialhaving more cracking activity than alumina; such materials are moreacidic than alumina. Examples of such catalysts include theplatinum-halogen-alumina catalysts of US. Patent 2,479,109, especiallywhere such disclosed catalysts contain at least 1 percent by Weight ofthe disclosed halogen, such as chlorine or fluorine, or both since thehigher amount of halogen gives a more acidic catalyst having morecracking activity. Other examples of applicable highly acidic catalystsare the catalysts disclosed in US. Patent 2,478,916, such as theplatinum or palladium deposited on a cracking component disclosed inthat patent, e.g., silica-alumina, silica-zirconia, silicamagnesia,silica-thon'a, silica-alumina-Zirconia, aluminaboria, etc. Examples ofspecific catalysts of specific portions disclosed in the foregoingpatents are also examples of catalysts applicable in either step of theprocess of my invention. A now particularly preferred catalyst for usein each step of the process of my invention is a catalyst consisting of0.05 to 5 weight percent platinum, about 1-10 weight percent of ahalogen, either chlorine or fluorine, or both, deposited on alumina.Specific examples of catalyst bases comprising a cracking componenthaving more cracking activity and being more acidic than pure aluminum,on which there is deposited one of platinum, palladium, rhodium,iridium, nickel and cobalt to produce a preferred catalyst of myinvention, are silica-alumina, silica-zirconia, silica-magnesia,silicathoria, alumina-boria, silica-alumina-zirconia,silicaalumina-magnesia, silica-alumina-thoria, alumina containing from 1to weight percent chlorine or fluorine, or both, and silica-aluminacontaining 1 to 10 weight percent chlorine or fluorine, or both.

As is well known in the art, when hydrocracking over catalysts promotedwith noble metals, nickel or cobalt, improved results are obtained ifstocks containing appreciable sulfur compounds are first desulfurized.As is well known such a treatment is a mild hydrogenation effected underconditions which convert the sulfur compounds to H 8 and will reduce theolefin content of the feed, if present, but which hydrogenationconditions are too mild to hydrogenate aromatics present. Such apretreatment step is Well known in the art, and can be effected using acobalt-molybdate type catalyst, for instance. Such a pretreatment stepis an optional preliminary step to the practice of the presentinvention.

Example I Hydrotreated kerosene (boiling range 457-535 F.) having adensity at 20 C. of 0.82 was contacted vwth platinum-halogen-aluminacatalyst containing about 0.4 weight percent platinum and 3 percentfluorine. One run was at about 842 F. and 500 p.s.i.g., and the otherwas at 779 F. and 800 p.s.i.g. Results of these tests were:

4 At 842 F. and 500 p.s.i.g. the gasoline had high octane rating;however, the high density (0.97) or" the residue above 400 F. shows thatit is highly aromatic and thus is comparatively stable at theseconditions. On the other hand the gasoline product from the run at 779F. and 800 p.s.i.g. had fairly low octane rating, but the residue above400 F. had about the same density as the feed showing that it can berecycled and further converted to these conditions.

Example II This example shows that gasoline produced at thelow-temperature, high-pressure conditions of my second step is upgradedwhen processed at the high-temperature, lower-pressure conditions of thefirst step.

Hydrotreated kerosene similar to Example I was contacted with aplatinum-boria-alumina catalyst containing about 0.4 weight percentplatinum and 11.8 percent boria at 705-744 E, 800 p.s.i.g., 2 L.H.S.V.,and with about 3400 cubic feet of H per barrel of kerosene. The 200400F. gasoline product, having an octane rating (Research +3 mm. TEL) of75.1, was then further processed by contacting with a similarplatinum-boria-alumina catalyst at 500 p.s.i.g. and 839 F. The octanerating of the gasoline was considerably improved as is shown by thefollowing data:

Process conditions:

Research +3 ml. TEL rating of gasoline product 97.6 Example 1HHydrotreated kerosene similar to that used in Examples 1' and ll wasprocessed over the same catalyst used in Example 11 at 768 F., 2L.H.S.V., 800 p.s.i.g., and with about 3400 cubic feet of hydrogen perbarrel of hydrocarbon. Approximately 630 volumes of feed containingabout 51 liquid volume percent of aromatics were treated. The productboiling above 400 F., which was equal to 11.0 liquid volume percent ofthe feed, contained 7.5 volume percent aromatics. Thus, approximately94.5 volumes (of the original 630) of aromatics boiling above 400 F.were fed to the hydrocracking step, and only about 5 volumes remained inthe product boiling above 400 F. This is especially significant sincethe temperature was in the upper part of the range (600780 E). Thedensity of the 400 F. product was 0.7926 using the 768 F. reactiontemperature. When the run was repeated as before, but using atemperature of 744 F. the density was 0.7835, indicating still loweraromatic content.

Example IV A hydrocarbon cut having a boiling range from 400 700 F. ischarged continuously to a hydrocracking reactor containing these samecatalysts described in Example I, employing a liquid hourly spacevelocity of 2, 500 p.s.i.g., 850 F. and a charge of 4000 cubic feet ofhydrogen under standard conditions per barrel of feed charged. From thereaction product is separated the material boiling below 400 F., and thebalance of the product boiling above 400 F is charged to a secondhydrocracking reactor over a hydrocracking catalyst as described inExample II. In this reactor the conditions are a space velocity of 1, atemperature of 730 F., a pressure of 800 p.s.i.g. and 7000 cubic feet ofhydrogen per barrel of total charge. There is separated from the productof the second hydrocracking reaction the gasoline cut boiling in therange from 200 to 400 F, and this cut is continuously recycled to thefirst hydrocracking reactor as a part of the charge thereto, while thesmall portion of residue boiling above 400 F. is recycled to the secondhydrocracking reactor as part of the charge to that reactor.

As will be evident to those skilled in the art, various modifications ofthis invention can be made or followed in the light of the foregoingdisclosure and discussion without departing from the spirit and scope ofthe disclosure or from the scope of the claims.

1 claim:

1. A process for conversion of hydrocarbons which comprises the step-sof hydrocracking a hydrocarbon feed having a boiling range in the rangefrom 400 to 1000" F, together with a heavy gasoline recycle feeddescribed hereafter, in the presence of a hydrocracking catalystcontaining 110 weight percent of a group VIII metal selected from thegroup consisting of platinum, palladium, rhodium, iridium, nickel andcobalt deposited on a solid inorganic metal oxide cracking component,under conditions favoring dehydrogenation of naphthenes to aromatics,employing a temperature from 800 to 950 5., a pressure from 300 to 1000p.s.i.a., a liquid hourly space velocity of total hydrocarbon feed from0.2 to 10, and a ratio of hydrogen to total hydrocarbon feed of at least1000 s.c.f. per barrel; separating the residue fraction of the effluentboiling above 400 F. from the product gasoline fraction, hydrocrackingsaid residue in another hydrocracking step in the presence of a catalystof the foregoing description under conditions favoring hydrogenation ofaromatics to naphthenes, employing a temperature from 600 to 780 F, apressure from 500 to 2000 p.s.i.a., a liquid hourly space velocity oftotal hydrocarbon feed rom 0.2 to 10, and a ratio of hydrogen to totalhydrocarbon feed of at least 1000 sci. per barrel; separating a heavygasoline fraction from the eiliuent from said another hydrocracking stepand recycling same as part of the said total feed to the first-mentionedhydrocracking step.

2. A process of claim 1 wherein the residue boiling above 400 F. in saidanother hydrocracking step is recycled thereto as a part of the totalfeed thereto.

3. A process for conversion of hydrocarbons which comprises the steps ofhydrocracking a hydrocarbon feed having a boiling range in the rangefrom 400 to 1000 F., together with a heavy gasoline recycle feeddescribed hereafter, in the presence of a hydrocracking catalystcontaining 1-10 weight percent of a group VIII metal selected from thegroup consisting of platinum, palladium, rhodium, iridium, nickel andcobalt deposited on a solid inorganic metal oxide cracking componenthaving more cracking activity than pure alumina, under conditionsfavoring dehydrogenation of naphthenes to aromatics, employing atemperature from 800 to 950 F., a pressure from 300 to 1000 p.s.i.a., aliquid hourly space velocity of total hydrocarbon feed from 0.2 to 10,and a ratio of hydrogen to total hydrocarbon feed of at least 1000 s.c.f. per barrel; separating the residue fraction of the effluent boilingabove 400 F. from the product gasoline fraction; hydrocracking saidresidue in another hydrocracking step in the presence of a catalyst ofthe foregoing description under conditions favoring hydrogenation ofaromatics to naphthenes employing a temperature from 600 to 780 F, apressure from 500 to 2000 p.s.i.a., a liquid hourly space velocity oftotal hydrocarbon feed from 0.2 to 10, and a ratio of hydrogen to totalhydrocarbon feed of at least 1000 s.c.f. per barrel; separating a heavygasoline fraction from the effluent from said another hydrocracking stepand recycling same as part of the said total feed to the first mentionedhydrocracking step.

4. A process for conversion of hydrocarbons which comprises the steps ofhydrocracking a hydrocarbon feed havin a boiling range in the range from500 to 800 5., together with a heavy gasoline recycle feed describedhereafter, in the presence of a hydrocracking catalyst containing 1-10weight percent of a group VIII metal selected from the group consistingof platinum, palladium, rhodium, iridium, nickel and cobalt deposited ona solid inorganic metal oxide cracking component having more crackingactivity than pure alumina, under conditions favoring dehydrogenation ofnaphthenes to aromatics, employing a temperature from 800 to 950 F., apressure from 300 to 1000 p.s.i.a., a liquid hourly space velocity oftotal hydrocarbon feed from 0.2 to 10, and a ratio of hydrogen to totalhydrocarbon feed of at least 1000 s.c.f. per barrel; separating theresidue fraction to the effluent boiling above 400 F. from the productgasoline fraction; hydrocracking said residue in another hydrocrackingstep in the presence of a catalyst of the foregoing description underconditions favoring hydrogenation of aromatics to naphthenes employing atemperature from 600 to 780 F, a pressure from 500 to 2000 p.s.i.a., aliquid hourly space velocity of total hydrocarbon feed from 0.2 to 10,and a ratio of hydrogen to total hydrocarbon feed of at least 1000 s.c.fper barrel; separating a heavy gasoline fraction boiling in the range offrom 200 to 400 F. from the efiluent from said another hydrocrackingstep and recycling same as part of the said total feed to the firstmentioned hydrocracking step.

5. A process for conversion of hydrocwbons which comprises the steps ofcatalytically hydrocracking a hydrocarbon feed having a boiling range inthe range from 400 to 1000 F., together with a heavy gasoline recyclefeed described hereafter, under conditions favoring dehydrogenation ofnaphthenes to aromatics, employing a temperature from 800 to 950 F, apressure from 300 to 1000 p.s.i.a., a liquid hourly space velocity oftotal hydrocarbon feed from 0.2 to 10, and a ratio of hydrogen to totalhydrocarbon feed of at least 1000 s.c.f. per bar-rel; separating theresidue fraction of the effluent boiling above 400 F. from the productgasoline fraction; catalytically hydrocracking said residue in anotherhydrocracking step under conditions favoring hydrogenation of aromaticsto naphthenes, employing a temperature from 600 to 780 F., a pressurefrom 500 to 2000 p.s.i.a., a liquid hourly space velocity of totalhydrocarbon feed from 0.2 to 10, and a ratio of hydrogen to total hydrocarbon feed of at 1000 s.c.f. per barrel; separating a heavy gasolinefraction from the eifiuent from said another hydrocracking step andrecycling same as part of the said total feed to the first-mentionedhydrocracking step.

6. A process for conversion of a hydrocarbon feed stock boiling in therange from 400 to 1000 F. which comprises subjecting same to a firsthydrocracking step under conditions effecting dehydrogenation ofnaphthenes therein to aromatics, from the product of said first stepseparating a residue boiling above 400 F. and subjecting same to asecond hydrocracking step under conditions effecting hydrogenation ofaromatics to naphthenes, from the product of said second step separatinga heavy gasoline fraction and recycling same as additional feed to saidfirst hydrocracking step.

References Cited in the tile of this patent UNITED STATES PATENTS1,995,604 Davis Mar. 26, 1935 2,009,717 Peck July 30, 1935 2,279,550Benedict et a1 Apr. 14, 1942 2,334,159 Friedman Nov. 9, 1943 2,360,622Roetheli Oct. 17, 1944 2,428,692 Voorhies Oct. 7, 1947 2,464,539Voorhies Mar. 15, 1949 2,479,109 Haensel Aug. 16, 1949 2,703,308 Obladet a1. Mar. 1, 1955

1. A PROCESS FOR CONVERSION OF HYDROCARBONS WHICH COMPRISIES THE STEPSOF HYDROCRACKING A HYDROCARBON FEED HAVING A BOILING RANGE IN THE RANGEFROM 400 TO 1000*F., TOGETHER WITH A HEAVY GASOLINE RECYCLE FEEDDESCRIBED HEREAFTER, IN THE PRESENCE OF A HYDRROCRACKING CATALYSTCONTANINING 1-10 WEIGHT PERCENT OF A GROUP V111 METAL SELECTED FROM THEGROUP CONSISTING OF PLATINUM, PALLADIUM RHODIUM, IRIDIUM NICKEL ANDCOBALT DEPOSITED ON A SOLID INORGANIC METAL OXIDE CRACKING COMPONENT,UNDER CONDITIONS FAVORING DEHYDROGENATION OF NAPHTHENES TO AROMATICS,EMPLOYING A TEMPERATURE FROM 800TO 950*F., A PRESSURE FROM 300 T 1000P.S.I.A., A LIQUID HOURLY SPACE VELOCITY OF TOTAL HYDROCARBON FEED FROM0.2 TO 10, AND A RATIO OF HYDROGEN TO TOTAL HYDROCARBONS FEED OF ATLEAST 1000 S.C.F. PER BARREL; SEPARATING THE RESIDUE FRACTION OF GTHEEFFLUENT BOILING ABOVE 400*F. FROM THE PRODUCT GASOLINE FRACTION,HYDROCRACKING SAID RESICUE IN ANOTHER HYDROCRACKING STEP IN THE PRESENCEOF A CATALYST OF THE FOREGOUNG DESCRIPTION UNDNER CONDICTIONS FAVORINGHYDROGENATION OF AROMATICS TO NAPHTHEHES, EMPLOYING A TEMPERATURE FROM600 TO 780*F., A PRESSURE FROM 500 TO 2000 P.S.I.A., A LIQUID HOURLYSPACE VEOLCITY OF TOTAL HYDROCARBON FEED FROM 0.2 TO 10, AND A RATIO OFHYDROGEN TO TOTAL HYDROCARBON FEED OF AT LEAST 1000 S.C.F. PER BARREL;SEPARATING A HEAVY GASOLINE FRACTION FROM THE EFFLUENT FROM SAID ANOTHERHYDROCRACKING STEP AND RECYCLING SAME AS PART OF THE SAID TOTAL FEED TOTHE FIRST-MENTIONED HYDROCRACKING STEPS.